Striatal and cortical acetylcholine release in vivo in rats with unilateral decortication: effects of treatment with monosialoganglioside GM1.

Striatal and cortical extracellular acetylcholine (ACh) and choline (Ch) levels were determined in samples collected under in vivo conditions using microdialysis in normal (naive) and decorticated rats treated with saline or the monoganglioside GM1. ACh and Ch were assayed using a sensitive high performance liquid chromatography technique coupled to a postcolumn reactor with immobilized enzymes. Picomole amounts of ACh could be measured in the presence of an acetylcholinesterase inhibitor (neostigmine) in the microdialysis perfusion medium (striatal ACh = 0.2-0.4 microM; cortical ACh = 0.03-0.04 microM). Ch was detected both in the presence and in the absence of neostigmine (striatal Ch = 0.5-0.6 microM; cortical Ch = 0.6-2 microM). ACh, but not Ch, was strongly stimulated by 100 mM of KCl included in the perfusion medium. Decortication produced by devascularization did not significantly modify the cortical or striatal basal levels of ACh. However, in the cortex, KCl produced a higher ACh stimulation in the GM1-treated than in the saline-treated decorticated or naive rats. The present results indicate that GM1-treatment increases the ability of cortical cholinergic terminals to release ACh and support the idea that trophic factors such as monoganglioside GM1 can promote recovery following injuries of the central nervous system.